Those intimately involved in the ATSC standards process are familiar with the multitude of acronyms and terms that television engineers deal with every day.  For those of us without engineering degrees (and even as a refresher for you technologists out there) here’s “ATSC from A to Z” – more than 400 acronyms and 240 terms and descriptions used in ATSC standards and recommended practices:

Acronym                   Definition


A/D                             Analog to Digital

A/V                             Audio/Video

ABNF                          Augmented Backus-Naur Form

ACATS                        Advisory Committee on Advanced Television Service

ACE                             Active Constellation Extension

ACI                              Adjacent Channel Interference

ACK                             Acknowledgement

Ad-ID                          Format identifier for identifying advertising assets

AEA                             Advanced Emergency Alerting

AEAT                          Advanced Emergency Alert Table

AES                             Advanced Encryption Standard

AFD                             Active Format Description

AGC                             Automatic Gain Control

AGL                             Above Ground Level

ALC                             Asynchronous Layered Coding

AL-FEC                       Application Layer Forward Error Correction

ALP                             ATSC Link-Layer Protocol

ALPTP ALP                 Transport Protocol

AMC                            Adaptive Modulation and Coding

AMP                            Application Media Player

AP                               Additional Parity

APD                             Associated Procedure Description

API                              Application Programming Interface

ARQ                            Automatic Repeat-reQuest

ASL                             American Sign Language

ATSC                           Advanced Television Systems Committee

AWGN                         Additive White Gaussian Noise


BAT                             Broadcast Access Terminal

BBP                             Base Band Packet

BCH                             Bose, Chaudhuri, Hocquenghem

BCH (n, k, t)                Bose-Chaudhuri-Hocquenghem Error Correction Code having an n-bit codeword with k information bits (and hence n-k parity check bits) that is able to correct up to t bit-errors in the information bits.

BCI                              Broadcast Control Information

BEB                             Binary Exponential Backoff

BER                             Bit Error Rate

BICM                           Bit-Interleaved and Coded Modulation

BIL                              Bit InterLeaver

BMFF                          Base Media File Format

BP                               Bandpass

bpcu                            bits per cell unit

BPPS                           Baseband Packetizer Packet Set

bps                              bits per second

BPSK                           Binary Phase Shift Keying

BRET                          Bootstrap Reference Emission Time

BS                                Bootstrap

BSID                            Broadcast Stream ID

bslbf                            bit stream, left-most bit first

BSR                             Baseband Sampling Rate

BTC                             Broadcast Test Center

BTS                             Broadcast Television Station

BXF                             Broadcast eXchange Format


C                                  Center (audio channel)

C/I                              Carrier to Interference ratio

C/N                             Carrier-to-Noise ratio

CA                               Certificate Authority

CAP                             Common Alerting Protocol

CAZAC                        Constant Amplitude Zero Auto-Correlation

CC                               Closed Captions

CCI                              Co-Channel Interference

CCIR                            Consultative Committee on International Radio

CD                               ATSC 3.0 Companion Device

CDL                             Convolutional Delay Line

CDM                            Consumption Data Message

CDN                            Content Delivery Network

CDU                            Consumption Data Unit

CEA                             Consumer Electronics Association

CENC                          Common ENCryption

CFF                             Common File Format

CFO                             Center Frequency Offset

CID                              Context Identifier

CL                                Core Layer

Cod                             Code rate

CP                               Continual Pilot

CP                               Codepoint

CP                               Cyclic Prefix

C-POL                         Circular Polarization

CRC                             Cyclic Redundancy Check

CRI                              Clock Relation Information

CSRC                           Contributing Source Identifier

CSS                              Cascading Style Sheets

CSS                              Cascading Style Sheets

CTA                             Consumer Technology Association

CTC                             Convolutional Turbo Code

CTI                              Convolutional Time Interleaver

CVS                             Coded Video Sequence

CW                              Continuous Wave


D/A                             Digital to Analog

D/U                             Desired/Undesired ratio

DASH                          Dynamic Adaptive Streaming over HTTP

DASH-IF                     DASH Industry Forum

dB                               deciBel

dBµV                           dB above 1 µV

dBm                            deciBels referenced to 1 milliwatt

dBm                            dB above 1 mW

DC                               Direct Current

DDE                            Data Delivery Event

DECE                          Digital Entertainment Content Ecosystem

Demux                        Demultiplexer

DFT                             Discrete Fourier Transform

DMD                           Dynamic MetaData

DNS                             Domain Name System

DRC                             Dedicated Return Channel

DRC                             Dynamic Range Control

DRCT                          Dedicated Return Channel Table

DSBSS                         Direct Sequence Buried Spread Spectrum

DSCP                           Data Source Control Protocol

DSL                             Digital Subscriber Line

DSS                             Data Source Signaling

DSTP                           Data Source Transport Protocol

DTCP                          Digital Transmission Content Protection

DTV                             Digital Television, nominally ATSC 1.0

DUT                            Device Under Test

DWD                           Distribution Window Description


EA                               Emergency Alert

EAA                             Emergency Alert Application

EAM                            Emergency Alert Message

EAS                             Emergency Alert System

EBn                             Elementary Stream Buffer (nth instance)

EBU                             European Broadcast Union

ECC                             Error Correction Coding

ECDHE                        Elliptic Curve Diffie-Hellman Ephemeral key exchange

ECDSA                        Elliptic Curve Digital Signature Algorithm

EFDT                           Extended File Delivery Table

EHFR                          Efficient High Frame Rate

EIDR                           Entertainment Industry Data Registry

EL                                Enhanced Layer

eMBMS                       enhanced Multimedia Broadcast/Multicast Service

EMDF                          Extensible Metadata Delivery Format

EME                            W3C Encrypted Media Extensions

EMI                             Electromagnetic Interference

E-POL                         Elliptical Polarization

ERP                             Effective Radiated Power

ESG                             Electronic Service Guide

ESR5                           Erroneous-Second Ratio

ëXû                              The greatest integer less than or equal to X


FBSR                           FeedBack Shift Register

FCC                             Federal Communications Commission

FDD                             File Delivery Description

FDM                            Frequency Division Multiplexing

FDT                             File Delivery Table

FEC                             Forward Error Correction

FET                             Field Effect Transistor

FFT                             Fast Fourier Transform

FI                                 Frequency Interleaver

FIFO                            First-In-First-Out

FLUTE                        File Delivery over Unidirectional Transport

fps                               frames (or pictures) per second


Gbps                           Gigabits per second

GBR                             Guaranteed Bit Rate

GCM                            Galois Counter Method

GHz                             Gigahertz

GI                                Guard Interval

GNSS                           Global Navigation Satellite System

GoP                             Group of Pictures

GP                               Guard Period

GT                               Guard Time

GPS                             Global Positioning System

GUI                              Graphical User Interface


HAAT                          Height Above Average Terrain

HAGL                          Height Above Ground Level

HbbTV                        Hybrid Broadcast Broadband Television

HD                               High Definition

HDMI                          High-Definition Multimedia Interface

HDR                            High Dynamic Range

HD-SDI                       High Definition Serial Digital Interface

HDTV                          High-Definition Television

HELD                          HTML Entry pages Location Description

HEVC                          High Efficiency Video Coding

HFR                             High Frame Rate

HLG                             Hybrid Log-Gamma

HOA                            Higher Order Ambisonics

H-POL                         Horizontal Polarization

HRBM                         Hypothetical Receiver Buffer Model

HTI                              Hybrid Time Interleaver

HTML                         HyperText Markup Language

HTML5                       Hyper Text Markup Language, rev 5

HTTP                          Hyper-Text Transport Protocol

HTTPS                        Secure Hyper Text Transfer Protocol

Hz                               Hertz


I/Q                              In-phase / Quadrature

IANA                           Internet Assigned Numbers Authority

ID                                Identifier

ID                                Identification

IDFT                            Inverse Discrete Fourier Transform

IDR                              Instantaneous Decoding Refresh

IEEE                            Institute of Electrical and Electronic Engineers

IERS                            International Earth Rotation and Reference Systems Service

IETF                            Internet Engineering Task Force

IF                                 Interleaving Frame

IF                                 Intermediate Frequency

IFFT                            Inverse Fast Fourier Transform

IGMP                           Internet Group Management Protocol

IMSC1                         Internet Media Subtitles and Captions Version 1

IP                                Internet Protocol

IP3                              Third-Order Intermodulation Products

IPF                              Immediate Play-out Frame

IPTV                            Internet Protocol Television

IR                                Infra-Red

IR                                Initialization and Refresh

IR-DYN                       IR Dynamic

IS                                 Initialization Segment

ISO                              International Organization for Standardization

ISO BMFF                   ISO Base Media File Format

ISO/IEC                      International Organization for Standardization / International Electrotechnical Commission

ISOBMFF                    International Organization for Standardization Base Media File Format

ITI                               International Telecommunications Union

ITU-R                          International Telecommunication Union Radiocommunication Sector

ITU-T                          International Telecommunication Standardization Sector

IU                                Interleaving Unit


JSON                           JavaScript Object Notation


kHz                             kilohertz

kHz                             kilo Hertz


L                                  Left (audio channel)

L1                                Layer 1

LAN                             Local Area Network

LAPR                           Licensed-to-Average Power Ratio

LCT                             Layered Coding Transport

LDM                            Layered Division Multiplexing

LDPC                           Low-Density Parity Check

LED                             Light Emitting Diode

LF                                Left Front (audio channel)

LFE                             Low Frequency Effects (audio channel)

LFSR                           Linear Feedback Shift Register

LKFS                           Loudness, K-weighted, relative to Full Scale

LLS                              Low Level Signaling

LMT                            Layer Mapping Table

LMT                            Link Mapping Table

LPF                             Low Pass Filter

LR                               Left Rear (audio channel)

LS                                Left Side or Left Surround (audio channel)

LSB                             Least-Significant Bit

LTE                             Long Term Evolution


M&E                            Music and Effects

MA3                            MMT ATSC 3.0 Signaling Message

MAC                            Media Access Control

MAE                            Metadata Audio Elements

MBMS                         Multimedia Broadcast/Multicast Service

Mbps                           Megabits per second

MDCoIP                      Media Device Control over IP

MDE                            Media Delivery Event

MHAS                         MPEG-H Audio Stream

mhm1                         ISO Base Media File Format sample entry type for MPEG-H Audio Stream

MHz                            Megahertz

MIME                          Multipurpose Internet Mail Extensions

MIMO                          Multiple Input Multiple Output

MISO                           Multiple Input Single Output

MMT                           MPEG Multimedia Transport

MMTP                         MPEG Media Transport Protocol

Mod                            Modulation

MPD                            Media Presentation Description

MPEG                          Moving Pictures Experts Group

MPI                             Media Presentation Information

MPT                            MMT Package Table

MPU                            Media Processing Unit

MRC                            Maximum Retransmission Count

ms                               millisecond

MSB                            Most-Significant Bit

MSE                            W3C Media Source Extensions

µsec                            microsecond

MTU                            Maximum Transfer Unit

MTU                            Maximum Transmission Unit

Mux                             Multiplexer

MVPD                         Multichannel Video Programming Distributor


N/A                             Not Allowed

N/A                             Not Applicable

NACK                          Negative Acknowledgement

NAL                             Network Adaption Layer

NAL                             Network Abstraction Layer

NGA                            Next Generation Audio

NoA                             Number of Active (cells)

NoC                             Number of (useful) Carriers

NRT                            Non-Real Time

nsec                            nanosecond

NTP                             Network Time Protocol

NUC                            Non-Uniform Constellation


OAM                            Object Audio Metadata

OCSP                           Online Certificate Status Protocol

OFDM                         Orthogonal Frequency Division Multiplexing

OFDMA                       Orthogonal Frequency Division Multiple Access

OFI                              Optional Field Indicator

OMA                            Open Mobile Alliance

OMA BCAST               Open Mobile Alliance Broadcast Mobile Services Enabler Suite

OSD                             On-Screen Display

OSI                              Open Systems Interconnection

OSN                             On Screen message Notification

OTA                             Over The Air

OTI                              Object Transmission Information


PAM                            Pulse Amplitude Modulation

PAPR                          Peak-to-Average Power Ratio

PAT                             MPEG-2 Program Association Table

PC                               Personal Computer

PCM                            Linear Pulse Code Modulation. In this document this is understood to be the uncompressed format for audio signals.

PD                               ATSC 3.0 Primary Device

PDU                            Protocol Data Unit

PER                             Packet Error Rate

PH                               Phase Hopping

PHY                             Physical Layer

PID                              Packet Identifier

PIP                              Picture-in-Picture

PLP                             Physical Layer Pipe

PLP-R                         Physical Layer Pipe for Return Channel

PN                               Pseudo-Noise

ppm                            parts per million

PQ                               Perceptual Quantization

PRACH                        Physical Random Access Channel

PRBS                           Pseudo Random Bit Sequence

Pre                              Preamble

PSIP                            Program and System Information Protocol

PT                               Payload Type

PTP                             Precision Time Protocol

PUSCH                        Physical Uplink Shared Channel


QAM                            Quadrature Amplitude Modulation

QCI                              QoS Class Identifier

QoS                             Quality of Service

QP                               Quality Point

QPSK                           Quadrature Phase Shift Keying


R                                  Right (audio channel)

RAP                             Random Access Point

RCS                             relative cyclic shift

RDT                            ROHC-U Description Table

RDT                            ROHC-U Description Table

RF                               Radio Frequency

RF                               Right Front (audio channel)

RFC                             Request For Comment (IETF standard)

RFU                             Reserved for Future Use

RMP                            Receiver Media Player

RMS                            Root Mean Square

RNTI                           Radio Network Temporary Identity

ROHC                          RObust Header Compression

ROHC-U                      Robust Header Compression UDP

ROUTE                        Real-time Object delivery over Unidirectional Transport

ROUTE-DASH            Real-time Object delivery over Unidirectional Transport / Dynamic Adaptive Streaming over HTTP

RR                               Right Rear (audio channel)

RRM                            Reference Receiver Model

RRT                             Rating Region Table

RS                                Right Side or Right Surround (audio channel)

RSA                             A method for obtaining digital signatures and public-key cryptosystems (originally proposed by Rivest, Shamir, and Adelman).

RT                               Real Time

RTC                             Retransmission Count

RTP                             Real-time Transport Protocol

Rx                                Receiver


SAP                             Segment Access Point

SAP                             Secondary Audio Programming

SBS                              Subframe Boundary Symbol

SC-FDMA                    Single Carrier Frequency Division Multiple Access

SCG                             Standard Color Gamut

SCT                             Server Current Time

SD                               Standard Definition

SDO                             Standards Development Organization

SDR                             Standard Dynamic Range

SECP                           Standard for Efficient Cryptography Elliptic Curve Domain Parameters

SEI                              Supplemental Enhancement Information

SFN                             Single Frequency Network

SFR                             Standard Frame Rate

SG                                Service Guide

SGDD                          Service Guide Delivery Descriptor

SGDU                          Service Guide Delivery Unit

SHA                             Secure Hash Algorithm

SHVC                           Scalable High Efficiency Video Coding

SID                              Sub-stream Identifier

SIMO                           Single Input Multiple Output

SINR                            Signal to Interference plus Noise Ratio

SISO                            Single Input Single Output

SL-HDR1                    Single Layer High Dynamic Range part 1

SLS                              Service Layer Signaling

SLT                             Service List Table

SMPTE                        Society of Motion Picture and Television Engineers

SN                               Sequence Number

SNR                             Signal-to-Noise Ratio

SP                                Scattered Pilot

SPLP                           Single Physical Layer Pipe

SPS                              Sequence Parameter Set

SSDP                           Simple Service Discovery Protocol

SSM                             Source-Specific Multicast

SSM                             Service Signaling Manager

SSRC                           Synchronization Source Identifier

STL                             Studio-to-Transmitter Link

STLTP                         Studio–to-Transmitter Link Tunneling Protocol

S-TSID                        Service-based Transport Session Instance Description


TAI                              International Atomic Time

TAI                              Time Atomic International

TAI                              International Atomic Time

TASO                           Television Allocation Study Organization

TB                               Transport Block

TBI                              Twisted Block Interleaver

TBn                             Transport Buffer (nth instance)

tcimsbf                       two’s complement integer, msb first

TCP                             Transmission Control Protocol

TDCFS                         Time Diversity Code Filter Set

TDCFS                         Transmit Diversity Code Filter Set

TDM                            Time Division Multiplexing

TG-3                            Technology Group 3

TI                                Time Interleaver

TI                                Time Interval

TLS                             Transport Layer Security

T-MDE                        Transport Media Delivery Event

TOA                             Threshold of Audibility

TOC                             Table of Contents

TOI                              Transport Object Identifier

TOL                             Transport Object Length

TOV                             Threshold of Visibility

TPO                             Transmitter Power Output

TR                               Tone Reservation

T-RAP                         Transport-Random Access Point

TS                                Transport Stream

TSI                              Transport Session Identifier

TT                               Timed Text

TTA                             Telecommunication Technology Association

TTML                          Timed Text Markup Language

TV                               Television

TUID                           Temporary User ID

Tx                                Transmitter

TxID                            Transmitter Identification


U/L                             Uplink

UDP                            User Datagram Protocol

UHD                            Ultra High Definition

UHDTV                       Ultra High Definition Television

UHF                            Ultra High Frequency

UI                                User Interface

uimsbf                        unsigned integer, most significant bit first

UL-MAP                      Uplink Resource MAP

UML                            Unified Modeling Language

URCR                          Usage Reporting-Capable Receiver

URI                              Uniform Resource Identifier

URL                             Uniform Resource Locator

URN                            Uniform Resource Name

US                               United States

USB                             Universal Serial Bus

USBD                          User Service Bundle Description

USBD/USD                 User Service Bundle Description / User Service Description

UTC                             Universal Coordinated Time

UUID                           Universally Unique Identifier


VDS                             Video Description Service

VHF                             Very High Frequency

VP1                             The audio watermarking technology specified in A/334, “ATSC Standard: Audio Watermark Emission”

V-POL                         Vertical Polarization

VPS                             Video Parameter Set

VSWR                         Voltage Standing Wave Ratio

W3C                            World Wide Web Consortium


W3C                            World Wide Web Consortium

WAN                           Wide Area Network

WCG                            Wide Color Gamut


XLink                          XML Linking Language

XML                            eXtensible Markup Language

XOR                             eXclusive OR

XSL                              eXtensible Stylesheet Language


YAATE                        You’re almost at the end


ZC                                Zadoff-Chu


µs                                microsecond

µsec                            microsecond

16K                             16384 point FFT size

16QAM                       16-ary Quadrature Amplitude Modulation

2D                               Two dimensional

32K                             32768 point FFT size

3D                               Three dimensional

3GPP                           3rd Generation Partnership Program

8K                               8192 point FFT size





Active Area

The portion of the video picture area that is being utilized for program content. Also referred to in CTA-CEB16 as the useful image inside the video frame. Active area excludes letterbox bars and pillar box bars.

Adaptation Set

A set of interchangeable encoded versions of one or several media content components

Additional Header

An Additional Header is part of the ALP packet header. The presence of an Additional Header depends on the specific fields of the Base Header.

Additional View

Stereoscopic 3D video component using equivalent or lower resolution compared to the reference view video. The view can be provided together with the reference view to create an asymmetric 3D video. (E.g. reference view: UHD resolution, additional view: HD resolution).

Advanced Emergency Alert

Provides an emergency notification mechanism in ATSC 3.0 that is capable of forwarding a broad range of emergency data.

Alternative Presentation

A Presentation that supports the personalized audio use-case by providing alternative object properties to be used in combination with common object essences.


A time interval approximately equal to one millisecond derived from a binary count of nanoseconds and actually equaling 220 nanoseconds, which represents 1,048,576 nanoseconds (i.e., having a Period of 1.048576 milliseconds).

Analyzed Media Duration

The shortest Period between times at which data segment boundaries in all data Streams on the inputs of a Scheduler align. Data segment boundaries are indicated to the Scheduler by markers carried in the headers of the structures transporting data to the Scheduler.



App-Based Feature

Service component consisting of an application, optional files to be used by the application, and optional notifications directing the application to take particular actions at particular times.

App-Based Service

Service consisting entirely of app-based features, which provide the user interface for the service.


A.) A collection of documents constituting a self-contained enhanced or interactive service. The documents of an application can include HTML, JavaScript, CSS, XML and multimedia files. An application can access other data that are not part of the application itself. An Application is a special case of a locally cached content item and can be delivered via broadcast or broadband. B.) A downloaded collection of interrelated documents intended to run in the application environment specified in the A/344, “Interactive Content” and perform one or more functions, such as providing interactivity or targeted ad insertion. The documents of an application can include (but are not limited to) HTML, JavaScript, CSS, XML and multimedia files. An application can access other data that are not part of the application itself.


Application Context Cache

The Application Context Cache is a conceptual storage area where information from the broadcast is collected for retrieval through the Receiver Web Server. This document refers to the Application Context Cache as if it were implemented as actual storage though this is for convenience only. An Application Context Cache corresponds to the Application Context Identifier associated with each Broadcaster Application. Files delivered over ROUTE contain attributes that determine which Application Context Cache they will be associated with.

Application Context Identifier

An Application Context Identifier is a unique URI that determines which resources are provided to an associated Broadcaster Application by the Receiver. Resources may be associated with multiple Application Context Identifiers but a Broadcaster Application is only associated with a single Application Context Identifier. Details of the Application Context Identifier syntax are specified in the HELD.


Any multimedia data entity that is associated with a unique identifier and that is used for building a multimedia presentation.

ATSC 3.0 Bootstrap

The ATSC 3.0 Bootstrap provides a universal entry point into a broadcast waveform.

ATSC 3.0 Server

Any IP-connected device that provides content or other service to an ATSC 3.0 client, and that complies with the normative requirements of this standard.

ATSC Physical Layer Time (clock)

The ATSC Physical Layer Time is the time-scale described by the emitted ATSC Physical Layer Time samples, and corresponds exactly in rate with International Atomic Time (TAI).

ATSC Physical Layer Time (sample)

A sample time for ATSC Physical Layer Time is transmitted in the preamble. This data indicates the moment when the start of the first symbol of the immediately preceding bootstrap was emitted.

Audio Element

The smallest addressable unit of an audio Program.

Audio Presentation

Has the meaning given in the ATSC A/342 Audio, Part 1: Common Elements. Also referred to as a Preselection (DASH-IF), a Presentation (AC-4), or a Preset (MPEG-H).

Audio Program Component

Logical group of one or more Audio Elements that is used to define an audio Presentation, e.g., complete main, music & effects, dialog, etc.

Audio Signal

A.) Has the meaning given in the ATSC A/342 Audio, Part 1: Common Elements. B.) Has the meaning given in the “ATSC Standard: Audio Common Elements (A/342 Part 1)”.


Audio Watermark

Data which is embedded in audio essence in such a way that it can be extracted (i.e., read) by an appropriately designed extractor.

Author Signature

A signature encoded in a specified form that is generated by the author of the application, which is the entity or entities whom claim authorship over the application content.

Base Field

The first portion of a Baseband Packet Header.

Base Header

A Base Header is part of the ALP packet header. A Base Header is always included in the header of an ALP packet and the first part of an ALP packet.

Base URI

The Base URI specifies the initial portion of a URL used by the Broadcaster Application to access files within the Application Context Cache. The Base URL is prepended to the relative URI path of a file to obtain the full URL of the file within the Application Context Cache. The Base URI is uniquely generated by the Receiver based on the Application Context Identifier defined for the Broadcaster Application.

Baseband Packet

A set of Kpayload bits which form the input to a FEC encoding process. There is one Baseband Packet per FEC Frame.

Baseband Packet Header

The header portion of a Baseband Packet.


Baseband Packetizer

Functional block that creates Baseband Packets.



An ATSC 3.0 receiver with a DRC terminal module in it, or equivalently a DRC-enabled ATSC 3.0 receiver.


Block Interleaver

An interleaver where the input data is written along the rows of a memory configured as a matrix, and read out along the columns.


A defined sequence of symbols that introduces each Physical Layer frame and provides a universal entry point into a digital Transmission signal. Each Bootstrap carries a value that serves as an indicator of the format of an immediately following Preamble symbol.

Bootstrap Reference Emission Time

A time value indicating the instant at which the leading edge of the first symbol of a Bootstrap is to be emitted from the transmitting antenna(s), absent any timing offsets of individual Transmitter(s) in a Network.

Bootstrap Signaling (Information)

Synonymous with Low Level Signaling (LLS) information implemented by the Service List Table (SLT) in support of rapid RF channel scanning and service acquisition by the receiver through discovery of Service Layer Signaling (SLS) information.

Broadcast Gateway

A Broadcast Gateway converts source file objects, for example media, system information, and other opaque files, into SFN baseband description for distribution to Transmitters.

Broadcast Stream

The abstraction for an RF Channel which is defined in terms of a carrier frequency centered within a specified bandwidth.

Broadcast Stream ID

Identifier of a broadcast stream, as defined in Section 6.3.2 of A/331.


Broadcast Stream ID (BSID)

A 16-bit value that identifies the aggregate contents of a broadcast signal. Each transmitted signal that is unique (has content that is different from another signal) has a unique BSID; e.g., a signal translated onto a different frequency has the same BSID.

Broadcaster Application

A Broadcaster Application is used herein to refer to the functionality embodied in a collection of files comprised of an HTML5 document, known as the Entry Page and other HTML5, CSS, JavaScript, image and multimedia resources referenced directly or indirectly by that document, all provided by a broadcaster in an ATSC 3.0 service. The Broadcaster Application refers to the client-side functionality of the broader Web Application that provides the interactive service. The distinction is made because the broadcaster only transmits the client-side documents and code. The server-side of this broader Web Application is implemented by an ATSC 3.0 receiver and has a standardized API for all applications. No server-side application code can be supplied by the broadcaster. The broadcaster may provide Web-based documents and code that work in conjunction with the Broadcaster Application over broadband making the Broadcaster Application a true Web Application. The collection of files making up the Broadcaster Application can be delivered over the web in a standard way or can be delivered over broadcast as packages via the ROUTE protocol.


An ATSC 3.0 transmitter with a DRC base station module in it, or equivalently a DRC-enabled ATSC 3.0 transmitter.


Byte-Range-based File Repair

The method of file repair whereby in the event of incomplete file reception over broadcast delivery, the receiver, as the file repair client, calculates the byte range(s) corresponding to the missing source symbols, and uses HTTP partial GET (or nominal HTTP GET) to retrieve that data from the repair server. The repair server, as a conventional HTTP server, is AL-FEC unaware, and stores the file object as the resource to be returned in part or in whole according to the client request.


A.) One set of encoded I/Q components in a constellation. B.) A complete transmission of an independently recoverable packet of data in an audio watermark. C.) Has the meaning given in the ATSC A/334 Audio Watermark Emission specification.



Cell Interleaver

An interleaver operating at the cell level.

Center Frequency

The point in the spectrum of a Physical Layer signal at which equal numbers of carriers are positioned both higher and lower in the spectrum.


A system consisting of an encoder and decoder

Coded Video Sequence

Sequence parameter sets which apply to a series of consecutive coded video pictures.

Combined PLP

A PLP after processing by the LDM injection block.

Concatenated Code

A code having an Inner Code followed by an Outer Code.


A set of encoded (I component/Q component) points in the I/Q plane.

Content fragment

Portion of Service Announcement that describes ATSC program or content item, corresponding to Content fragment in OMA BCAST Service Guide model, with additions and constraints.

Content item

Set of one or more files which a service provider intends to be treated as a single unit for presentation purposes.


RFC 3095 describes Context, as used herein, in the following mnner: The context of the compressor is the state it uses to compress a header. The context of the decompressor is the state it uses to decompress a header. Either of these or the two in combination are usually referred to as “context,” when it is clear which is intended. The context contains relevant information from previous headers in the packet stream, such as static fields and possible reference values for compression and decompression. Moreover, additional information describing the packet stream is also part of the context, for example information about how the IP Identifier field changes and the typical inter-packet increase in sequence numbers or timestamps.

Contribution Encoding

An audio encoding format that is configured for the purpose of distributing broadcast audio within and among professional broadcast environments, where multiple stages of encoding and decoding are expected to be performed.

Core Layer

The first layer of a 2-layer LDM system. The only layer in a non-LDM system.

Core PLP

A PLP belonging to the Core Layer.

DASH Client

A DASH Client per the DASH-IF profile.

DASH Media Presentation

A DASH Media Presentation per the DASH-IF profile.


DASH Media Presentation Description (MPD)

A DASH MPD per the DASH-IF profile.




DASH Media Segment

A DASH Media Segment per the DASH-IF profile


DASH Period

A DASH Period per the DASH-IF profile.

DASH Representation

A DASH Representation per the DASH-IF profile.


DASH Segment

Refers to a DASH Initialization Segment or Media Segment per the DASH-IF profile.

Data Consumer

A device that receives a formatted stream of data and further processes and/or distributes it.

Data Delivery Event (DDE)

A Data Delivery Event (DDE) is the result of a block based MAC/PHY delivering relevant contents of a specific physical layer block to a specific ROUTE session at specific time.

Data Payload Symbols

Data and Subframe Boundary Symbols (i.e. non-Preamble symbols).


Data Producer

A device or process that generates a formatted stream of data.

Data Source

An origination point for data to be transmitted as content by the Physical Layer.

Data Source Signaling

Information sent from a Data Source to downstream functions to identify specific characteristics of the content of certain packets within the data Stream to provide interlayer communications while avoiding layer violations in the system. Typically, Data Source Signaling information is carried in RTP headers in locations defined in this standard.



Default Video

For a Service that includes multiple video assets, indicates the video preferred by the service provider for selection in the absence of an action, instruction or configuration to make an alternate selection.

Distributor Signature

A signature encoded in a specified form that is generated by a distributor, which is a third party (e.g., the broadcaster) that is distributing the application on behalf of the author.

DRC Downlink

Downlink signaling and downlink data transmission of DRC-related information through the PLP for Return Channel (PLP-R).


DRC Uplink

Uplink signaling and uplink data transmission of DRC through the Physical layer and MAC layer specifications defined in A/323.


Dynamic Event

Has the meaning given in A/337.

EA Service

Service that delivers rich media resources that are referenced in an emergency alert CAP message.

Earliest Time

A time value that accompanies data sent as input to a Broadcast Gateway to indicate the first instant, as determined using TAI, at which the first byte of related data, including all wrappers and encapsulating protocols, may start emission on the Physical Layer.


The process whereby an audio signal is modified to include an audio watermark.




A tool or process that is able to embed an audio watermark in an audio signal.

Emission Coding

An audio encoding format that is configured for the purpose of broadcast emission to receivers (viewers).

Emission Wakeup Field

The two Wakeup Bits in a Bootstrap when treated together as a field.


Enhanced Layer

The second layer of a 2-layer LDM system.

Enhanced PLP

A PLP belonging to the Enhanced Layer.

Entry Package

The Entry Package contains one or more files that comprise the functionality of the Broadcaster Application. The Entry Package includes the Entry Page and perhaps additional supporting files include JavaScript, CSS, image files and other content.

Entry Page

A.) An initial HTML5 document referenced by application signaling that should be loaded first into the User Agent. It is included as a file within the Entry Package. B.) The Entry Page is the initial HTML5 document referenced by application signaling that should be loaded first into the User Agent. The Entry Page is one of the files in the Entry Package.


ESG Service

Service that delivers Electronic Service Guide (ESG) information.


Timed notification to receiver software or to an application indicating that some action is to be taken

Event Stream

A.) Stream of events. B.) An Event Stream is a series of messages, either static, in DASH signaling, or dynamic, contained in defined messages within media segments. The events contained within the Event Stream can initiate interactive actions on the part of a Broadcaster Application.



An element of a Transmitter comprising data processing and signal processing functions including at least framing, error correction coding, waveform generation, modulation, and up-conversion to the output RF channel frequency.



Extended FDT Instance

An instance of the FLUTE FDT that includes extensions. The Extended FDT may be transported as the EFDT element within the Srcflow element, or as an FLUTE FDT-Instance element in TOI=0.

Extension Field

The third portion of a Baseband Packet Header.

Extension Header

An Extension Header is part of the ALP packet header. The presence of an Extension Header depends on the specific fields of the Additional Header.


A tool or process that is able to extract audio watermark packets from an audio signal.

FEC Block

A FEC Frame after mapping to cells.

FEC Frame

A single Baseband Packet with its associated FEC parity bits attached, having a total size of 64800 or 16200 bits (per FEC Frame).

Filter Code

An integer which represents a personalization description. Filter Codes are created by broadcasters according to broadcasters’ particular personalization categories, such as truck owner, sustaining member, or a zip code. Filter Codes are unique within the scope of an AppContextID described in A/344. Filter Codes may be associated with files.


One part of a fragmented ISOBMFF file

Frequency Interleaver

An interleaver which takes cells and interleaves them over a particular symbol.




A sequence of bits that is present at the start of a cell.

High Dynamic Range

A feature that allows representation of video levels with much higher luminance values than is possible with traditional video methods.

(HTTP) File Repair

HTTP transactions between the receiver and a network repair server, conducted over the broadband channel, which enables the receiver to recover partially delivered object(s).

I(x) mod G(x)

The remainder that results from the polynomial division of I(x) by G(x).


An independently decodable frame

Initialization Segment

Segment containing metadata that is necessary to present the media streams encapsulated in Media Segments.

Inner Code

One code of a Concatenated Code system.

Interlaced HD

A specific set of high definition video formats.


A device used to counteract the effect of burst errors.

Interval Code

A value that identifies the interval of content in which the VP1 payload value is embedded.

Large Domain

A division of the VP1 Payload wherein the interval field has a size of 25 bits, sufficient to support watermarking of approximately 1 year, 7 months of content.



Latest Time

A time value that accompanies data sent as input to a Broadcast Gateway to indicate the last instant, as determined using TAI, by which the last byte of related data, including all wrappers and encapsulating protocols, must complete emission on the Physical Layer.

Layered Division Multiplexing

A multiplexing scheme where multiple PLPs are combined in layers with a specific power ratio.

Legacy SD

A specific set of standard definition video formats.

Linear Audio/Video Service

Service consisting of one or more continuous video components, one or more continuous audio components, each associated with one or more of the video components, and one or more closed caption components, each associated with one or more of the audio components, all streamed in real time. May also contain app-based features.

Linear Audio-Only Service

Service consisting of one or more continuous audio components and one or more closed caption components, each associated with one or more of the audio components, all streamed in real time. May also contain app-based features.

LLS (Low Level Signaling)

Signaling information which supports rapid channel scans and bootstrapping of service acquisition by the receiver.

Locally Cached Content Item

A collection of one or more Locally Cached Files which are intended to be consumed as an integrated whole. A Locally Cached Content Item is typically not consumed or presented until the requisite Locally Cached Files have been fully received and cached.

Long-term storage

A location in memory used to store a recording of a program with the intention of playback at a later date and time. This memory is persistent through power cycles of the device.

Major Channel Number

Part of the identification of a service, as defined in Section 6.3.2 of A/331 as SLT.Service@majorChannelNo. The combination of major and minor channel number is unique within a broadcast area. I.e., a receiver of over-the-air broadcasts will never see two different services with the same major/minor channel number combination.

Marked Audio

Audio that has an audio watermark embedded in it.

Media Delivery Event (MDE)

A Media Delivery Event (MDE) is the arrival of a collection of bytes that is meaningful to the upper layers of the stack for example the media player and decoder(s). MDE data blocks have delivery deadlines. The grouping of bytes that is a RAP is a “Delivery” in ROUTE and the arrival of these bytes is an “Event” at an upper layer.

Media Presentation

Collection of essences that establishes a bounded or unbounded presentation of media content.

Media Presentation Description

Formalized description for a Media Presentation for the purpose of providing a streaming service.


Media Processing Unit

Generic container for independently decodable timed or non-timed data that is media codec agnostic.

Media Segment

A.) A portion of a data Stream that is treated as a unit by a Scheduler for purposes of analysis and Transmission. B.) Segment that complies with media format in use and enables playback when combined with zero or preceding Segments and a Initialization Segment (if any).


Minor Channel Number

Part of the identification of a service, as defined in Section 6.3.2 of A/331 as SLT.Service@minorChannelNo.

MMT Package

Logical collection of media data, delivered using the MMT protocol.

MMT Protocol

Application layer transport protocol for delivering MMTP payload over IP networks.

MMTP Packet

Formatted unit of the media data to be delivered using the MMT protocol.


A combination of modulation and code rate that together determine the robustness of the PLP and the size of the Baseband Packet.

MP Table

MMT Package Table containing information on MMT assets/content components.



MPI message

MMT signaling message containing an MPI Table.

MPI Table

MMT table containing presentation information.

MPT message

MMT signaling message containing an MP Table.


(Verb) to send data across (e.g., an IPv4) network to many recipients simultaneously; (noun) a set of data sent across (e.g., an IPv4) network to many recipients simultaneously.


A group of services that are transmitted together over a Network.


A group of Transmitters delivering the same Multiplex.

Network Content Item

A continuous component (e.g., an audio/video clip) or a collection of one or more files (e.g., a slide show or a set of inter-linked HTML pages) that is intended to be consumed as an integrated whole, and that is delivered on demand for immediate presentation. Network Content Items are delivered via broadband and are normally progressively presented prior to receiving the entire file(s).

Network Layer Packet

A Network Layer Packet is a source packet in the protocol of the data to be transported, e.g., an MPEG-2 Transport Stream packet or an Internet Protocol packet.

Non-Uniform Constellation

A constellation with a non-uniform spread of constellation points.

Null Packet

An MPEG-2 TS packet with PID equal to 0x1FFF.

Optional Field

The second portion of a Baseband Packet Header.

Outer Code

One code of a Concatenated Code system.


A.) A collection of data sent as a unit, including a header to identify and indicate other properties of the data, and a payload comprising the data actually to be sent, either having a fixed known length or having means to indicate either its length or its end. B.) Has the meaning given in the ATSC A/334 Audio Watermark Emission specification.

Packet Set

A group of packets carrying segments of a large data structure that has been segmented for the purpose of carriage across a transport connection that is not configured to carry the large data structure.


A process that treats a collection of data (e.g., a portion of a data Stream) by breaking it into segments and wrapping the segments in a header structure, thereby creating packets for Transmission / delivery.


The BTS pages for a single terminal in the broadcast network.



A division of the Cell that carries the BCH code parity check bits.


Linear Pulse Code Modulation. In this document this is understood to be the uncompressed format for audio signals.


A duration of time.


A feature that provides consumers control over the listening experience

Physical Layer

A functional protocol that defines the framing, resource allocation, and waveforms of signals emitted for delivery of data and content to receivers.

Physical Layer Pipe

A structure specified to an allocated capacity and robustness that can be adjusted to broadcaster needs.

PLP (Physical Layer Pipe)

A portion of the RF channel which has certain modulation and coding parameters.




A.) The portion of the frame that carries L1 signaling data for the frame. B.) The portion of a Physical Layer frame that carries L1 signaling data for the frame.


Preamble Generator

A function within a Broadcast Gateway that accepts instructions from a Scheduler, creates and formats Preamble Packets according to those instructions, and releases the Preamble Packets in the form of a Preamble Stream that can be multiplexed with other data Streams for delivery to the Transmitter(s) under control of the Broadcast Gateway.

Preamble Packet

A packet of data that provides a complete set of information necessary for Transmission following the Bootstrap of a Physical Layer frame to instruct receivers regarding the necessary receiver data processing to permit recovery of the data contained within the frame. The packet also serves to instruct Transmitters with respect to the configuration of the Physical Layer frame that is to be emitted so that the Exciter data processing for the frame can be properly configured.

Preamble Parser

A function within an Exciter that receives Preamble Streams, extracts from them Preamble Payload data, and stores the Preamble Payload data until the time for its emission as part of a broadcast signal. The Preamble Parser then makes the Preamble Payload data available to the Exciter control system for use in configuring the data- and waveform-processing of the Exciter, and outputs individual Preamble Packets at the correct times for their inclusion in the emission of the Physical Layer frames the configurations of which they define.

Preamble Payload

The L1 data carried in a Physical Layer frame to define the structure of the frame and to specify the modulation, coding, and other parameters used in delivery of the frame.

Preamble Stream

A data Stream carrying Preamble Packets, comparable to the data Streams carrying data for PLPs and for Timing and Management functionality, that can be multiplexed with other Streams and delivered as a combined data Stream that is tunneled through the STLTP.


A set of one or more AC-4 Substreams intended to be decoded and presented to the user simultaneously. In the context of this document, the term Presentation and the term Audio Presentation as defined in Part 1 of A/341, refer to identical concepts.

Primary Bit Stream

The elementary stream that serves as the entry-point. It carries the default Presentation in a multistream Program

Privileged Application

An application that can override system controls, authorizations, or privileges.



A single content segment

Progressive Video

A specific set of formats.


Protocol Data Unit

The protocol data unit encapsulated in the DRC Uplink MAC layer. The maximum size of a DRC uplink MAC PDU is limited to 2048 bytes.


Query Flag

The value of the query_flag field in an instance of the VP1 Payload.

Random Access

User terminals try to access the system.


Random Access Point (RAP)

A Random Access Point is the starting byte of a sequence of data that allows an applicable media client and decoder to start.


The Receiver described in this document refers to an entity that implements the functions of the Reference Receiver Model.

Receiver Web Server

The Receiver Web Server is a conceptual component of a Receiver that provides a means for a User Agent to gain access to files delivered over ROUTE that conceptually reside in the Application Context Cache.

Receiver WebSocket Server

The Receiver WebSocket Server provides a means for a User Agent to gain access to information about the Receiver and control various features provided by the Receiver.

Recovery File

A file containing signaling data about the service being presented including URLs that can be used to access signaling information for supplementary signaling and content.

Recovery File Server

A server that provides Recovery Files to receivers.


Reference Receiver Model

A conceptual receiver device that is capable of executing the APIs and behavior specified in this document. This document specifies normative attributes of the model, which are intended to inform actual receiver implementations.

Reference View

Stereoscopic 3D video component with the spatial resolution equal to or greater than the additional view.

Repair Symbol

A symbol containing information generated by the AL-FEC code which can be used to recover lost source symbols of the transport object.


A collection and encapsulation of one or more media streams in a delivery format and associated with descriptive metadata


Set aside for future use by a Standard.

Resource Block

A resource block is composed of 3 resource tiles that are contiguous in frequency-time dimension or time-frequency dimension.


Resource Tile

Basic unit in an uplink physical frame. One resource tile occupies 20 contiguous subcarriers in the frequency dimension and 2 contiguous symbols in the time dimension, which is equal to 40 cells. Among the cells in one resource tile, 8 of them are used for pilots and 32 are used for data transmission. Each resource tile has an index to represent it, which is numbered according to the position of the resource tile in the uplink frame.


Scalable/Layered Audio

An audio system that uses hierarchical techniques to: (1) Provide increasing quality of service with improving reception conditions, and/or (2) Provide different levels of service quality as required by different device types or presentation environments.

Schedule fragment

Portion of Service Announcement that describes presentation scheduling of content in an ATSC service, corresponding to Schedule fragment in OMA BCAST Service Guide model, with additions and constraints as described in this document.


A Studio side-function that allocates physical capacity to data Streams based on instructions from the System Manager combined with the capabilities of the specific system.


Unit of data associated with an HTTP-URL and optionally a byte range that are specified by a MPD.

Segment Index

Compact index of the time range to byte range mapping within a Media Segment separately from the MPD.

Server Code

A value that identifies a server which acts as the starting point for acquisition of supplementary content.


A collection of media components presented to the user in aggregate; components can be of multiple media types; a Service can be either continuous or intermittent; a Service can be Real Time or Non-Real Time; Real Time Service can consist of a sequence of TV programs.

Service Announcement

Service Announcement is information regarding the ATSC services and content available.

Service fragment

Portion of Service Announcement that describes ATSC service, corresponding to Service fragment in OMA BCAST Service Guide model, with additions and constraints.

Service Guide

Function of presenting Service Announcement.

Signaling Server

A server that provides access to the Service Layer Signaling (SLS), as specified in Section 7 of A/331.

Single Frequency Network

Multiple Transmitters in proximity to one another radiating the same waveform and sharing a frequency.

SLS (Service Layer Signaling)

Signaling which provides information for discovery and acquisition of ATSC 3.0 services and their content components.

SLT (Service List Table)

Table of signaling information which is used to build a basic service listing and provide bootstrap discovery of SLS.

Small Domain

A division of the VP1 Payload wherein the interval field has a size of 17 bits, sufficient to support watermarking of approximately 54 hours of content.

Source Symbol

A symbol containing information from the transport object.

Spatial Scalable Coding

A method of providing low and high spatial resolution versions of content through use of a base and an enhancement layer


A robustness feature that can be optionally added to audio components consisting of delivery of a redundant version of a main audio component, possibly coded with lower quality (lower bitrate, number of channels, etc.), and with a significant delay ahead of the audio with which it is associated. Receivers that support the Staggercast feature can switch to the Staggercast stream should main audio become unavailable. The delivery delay between Staggercast audio and main audio is chosen to be high enough to provide robustness thanks to sufficient time diversity between the two.

Standard Frame Rate

A picture frequency lower than or equal to 60 pictures per second.


STL Interface

The STL Interface is the origin point for the Studio-to-Transmitter Link Tunneling Protocol (STLTP).


A sequential set of packets carrying data from a Data Source to one or more Data Consumers.

Stream Access Point

Position in a Representation enabling playback of a media stream to be started using only the information contained in Representation data starting from that position onwards (preceded by initializing data in the Initialization Segment, if any)

S-TSID (Service-based Transport Session Instance Description)

An SLS XML fragment which provides the overall session description information for transport session(s) which carry the content components of an ATSC 3.0 service.


Studio Interface

The Studio Interface is the termination point for the ALP Transport Protocol (ALPTP) and/or the Data Source Transport Protocol (DSTP).


Unit within Media Segments that is indexed by a Segment Index.


A part of an AC-4 elementary stream that contains audio data and/or corresponding metadata. A Substream is referenced by one or more Presentations.


A.) A unit of data processed by an FEC code; e.g., N bytes of data. A symbol is always considered as a unit—i.e., it is either completely received or completely lost. B.) The representation of a bit of binary information in the audio watermark.


System Manager

The System Manager is a conceptual subsystem outside the Transport and Physical Layers and responsible for coordinating the functions of at least those two layers and the static and quasi-static configurations of various system aspects, for example definition of PLPs or assignment of IP addresses and port numbers to Services. The System Manager does not manage real-time traffic directly.


A property of a code in which the code word is composed of the original data in its sequential order followed by the parity data for the code word.

TI Block

An integer number of FEC Blocks.

Time Interleaver

An interleaver which takes cells and interleaves them over a particular time period.


A buffer of memory used to record a temporary, fixed duration of the program being presented for the purposes of skipping ahead, skipping back, pausing, or resuming playback of a broadcast.

Timing and Management Data

A collection of data sent from a Timing and Management Generator in a Broadcast Gateway to the Transmitter(s) under control of the Broadcast Gateway for purposes of controlling the emission times of Physical Layer frames, establishing various Transmitter configurations, and setting various Transmitter parameters, independent of the configurations of the frames and waveforms of the emitted signal itself.

Timing and Management Generator

A function within a Broadcast Gateway that accepts instructions from a Scheduler, creates and formats Timing and Management Data according to those instructions, and releases the Timing and Management Data in the form of a Timing and Management Stream that can be multiplexed with other data Streams for delivery to the Transmitter(s) under control of the Broadcast Gateway.

Timing and Management Stream

A data Stream carrying Timing and Management Data, comparable to the data Streams carrying data for PLPs and for Preambles, that can be multiplexed with other Streams and delivered as a combined data Stream that is tunneled through the STLTP.


A collection of related samples in an ISO base media file. For media data, a Track corresponds to a sequence of images or sampled audio.


The process by which audio that is represented in one encoding format is converted into another encoding format. This is typically achieved by decoding the audio from the first encoding format to PCM audio, followed by encoding of the PCM audio into the destination format.


The signal that is emitted by a Transmitter and the synchronized signal that is emitted by all Transmitters in a Network.


An individual emitter at a specific geographic location on a specific frequency.

Transport Block

The minimum channel coding block for uplink communications. The size of a transport block is determined by the number of allocated tiles for a user and the coding scheme. Referring to Table 5.5 of A/323, the maximum number of information bits transmitted by a transport block can be 96, 144, 192, 288, 384, 432, 576, or 864. When the size of a MAC PDU is less than or larger than this limitation, padding or segmentation, respectively, shall be used.


Transport Layer

A functional protocol that defines the formatting of data that will be delivered to receivers after its recovery from the formatting required for its physical delivery by the Physical Layer. It provides logical communication between application processes running on different hosts within a layered architecture of protocols and other network components.

Transport Media Delivery Event (T MDE)

A Transport Media Delivery Event is a Media Delivery Event wrapped in IP/UDP/ROUTE.


Transport Random Access Point (T RAP)

A Transport Random Access Point (T-RAP) is the first byte of a Random Access Point as expressed in IP/UDP/ROUTE transport.


Tunnel Packet

A packet that carries in its payload the contents of one or more multiplexed packet Streams, including the corresponding headers and any other structural elements, i.e., a packet in the “outer” layer of a packet Tunneling system.

Tunneled Data Stream

A Stream of multiplexed Tunneled Packets carried within an STLTP encapsulation for ECC processing.

Tunneled Packet

A packet within a multiplexed group of packet Streams carried in a Tunnel Packet, i.e., a packet in the “inner” layer of a packet Tunneling system.


A process by which a group of parallel and independent packet Streams are carried within a single packet Stream so that they can be processed, transported, and otherwise treated as a single Stream entity.


The combination of Internet Protocol (IP) addresses and port numbers.

Twisted Block Interleaver

An interleaver that performs intra-subframe interleaving by interleaving TI Blocks.



USBD/USD (User Service Bundle Description / User Service Description)

The XML-based SLS fragment which provides entry point information for the description and discovery of the technical details of an ATSC 3.0 service.



User Agent

Software provided by the Receiver that retrieves and renders Web content. The User Agent interprets HTML5, CSS, and JavaScript, renders media, text, and graphics, and can create user interaction dialogs.


The audio watermarking technology standardized in the ATSC A/334 Audio Watermark Emission specification.


VP1 Audio Watermark Segment

A continuous interval of watermarked audio during which signaling information recovered via audio watermark Payloads is applicable.


VP1 Message Group

A sequence of video frames, each carrying a vp1_message, each  carrying identical data repeated for all successive video frames across at least a 1/6 second duration of content.

VP1 Payload

The specific arrangement of the 50-bit VP1 payload in domain_type, server_field, interval_field, and query_flag specified in the present document.

VP1 Video Watermark Segment

A continuous interval of time that contains watermarked video during which signaling information recovered via vp1_message ()s is applicable.


VP1 Watermark Segment

A VP1 Video Watermark Segment or a VP1 Audio Watermark Segment.


Wakeup Alert

The occurrence of an AEA message requesting the setting of a non-zero value for the Emission Wakeup Field.

Wakeup Bits

The bits in Bootstrap Symbols 1 and 2 that are used to indicate to receivers that there is high-priority emergency information included in the broadcast.

Web Application

A Web Application is a client/server program accessed via the web using URLs. The client-side software is executed by a User Agent.

Wide Color Gamut

A feature that allows representation of chrominance levels with much broader range than is possible with BT.709.


Pop Quiz to follow.